共查询到20条相似文献,搜索用时 562 毫秒
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ChunXiaLI YingXiaLI LingBoYU HuaZHANG SiftDongCHU HuaShiGUAN 《中国化学快报》2003,14(8):776-778
A convenient synthetic route was developed for the synthesis of the novel glycolipids: 1,2-di-O-acyl-3-O-(2‘-acylamide-2‘-denxy-ct-D-glucopyranosyl)-sn-glycerols. 10 new compounds of glycolipids with different acyl groups were obtained. 相似文献
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GUO Ji-Yu YIN Da-Li GAO You-Song LIU Da-Kuan LIANG Xiao-Tian Institute of Materia Medica Chinese Academy of Medical Sciences Beijing 《有机化学》1993,(2)
Hainanensine(1) and its analog 6 were obtained through intramolecular regiospecific cycliza-tion. Reduction of 6 under different conditions gave 7~12. The stereochemistry was established bychemical correlation, spectral analysis and X-ray diffraction. 相似文献
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. Oxidation of β-hydroxy thioethers with MnO2-aqu. 35%/HCl in methanol gives β-hydroxy sulfoxides in high yields. 相似文献
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IntroductionPhotorefractive(PR)materialscanbeusedinvariousaPplications,suchasimageprocessing,highdensityopticaldatastorage,opticalinterconnects,andopticalphaseconjugations.However,mostofthereportedPRcomPositesaredopingsystems.ThephaseseparationofcomPonentshaslimitedtheirinvestigation.Toovercomethisdisadvantage,theuseofthemulti-propertieschromophoresmaybeoneoftheeffectiveapproaches.Merocyaninesarenotonlygoodphotoconductivedyes,butalsowidelyusedaschromophoresinnonlinearopticalLBfilmsduetothe… 相似文献
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Alligator sinensis and Alligator mississippiensis are put under the Alligator family and Alligator genus as two different species and have been thought that they are closely related in taxonomy. The results of our DNA-DNA hybridization experiments showed that A. sinensis is a relatively young species originated in Asia,whereas A. mississippiensis is the older.It seems that the alligator and crocodilian could evolve from each other.The evolutionary rate of the crocodilian is slower than those of birds and higher vertebrates.The phylogeny of four crocodilians have been obtained and the hypothesis that the ancestor of Crocodylus porosus is a transitional form between A.mississippiensis and A.sinensis is proposed. 相似文献
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Based on the information theory and multifractals viewpoint, the information dimension D_1 of acoustic emission (AE) of rock for marble, gabbro and sandstone in a laboratory condition and seismic activities before and after some large earthquakes are studied. The results show that there is a dimension reduction process before the failure of rock and before the occurrence of large earthquakes. The curves of D_1 determined during the process have a wider non-scaling range. Moreover, the non-scaling range became narrow when rock was close to failure fracture and large earthquake was just to happen. This shows that the system has instable critical behavior. 相似文献
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Prof. Dr. K. C. Nicolaou 《Angewandte Chemie (International ed. in English)》1993,32(10):1377-1385
The first total synthesis of calicheamicin γ was achieved approximately a year ago. In this article, the author presents a personal account of the events, in chronological order, that led to this success story in total synthesis. 相似文献
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PENG Shi-Qi DONG Ying Ekkehard Winterfeldt Beijing Medical University Beijing Institute of organic chemistry Hannover University 《有机化学》1993,(3)
Carboline was reduced with lithium aluminum hydride to provide carboline-alcohol whichreacted with methyl vinyl ketone to form the corresponding hydroxymethyl-amino-ketone. Underphase transfer condition it can be converted into enantiomerically pure indoloquinolizines. The cycliza-tion mechanism was also illustrated here. 相似文献
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Perfluoroalkyl-substituted tetrakisphenylporphyrins were synthesized through the couplingreaction of perfluoroalkyl iodides(R_FI)with the corresponding bromophenylporphyrin under theCu-bronze catalysis. 相似文献
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《有机化学》1993,(2)
The duality in electronic effect of sydnone ring and the effect of delocalization of 4-substitutedgroup to sydnone ring are investigated by the nitration of 3-benzyl-4-phenylsydnone and 4-formyl-3-arylsydnones. Sydnones are typical mesoionic compounds and their chemical, physical and biological properties 相似文献
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The title compound was prepared and its crystal structure was determined using X-ray crystallographic method. The crystal is orthorhombic, space group is P212121 with a= 1. 1114(2) nm, b=1.7677(3) nm, c=1.8312(3) nm; Z=8. The geometric structure and conformation of the title compound obtained by MMX molecular mechanics calculation are in agreement with those obtained from X-ray determination. 相似文献
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JOSEF Havel 《中国科学B辑(英文版)》2005,48(Z1)
In this paper, we develope the new standardization methods to eliminate the influence in capillary electrophoresis (CE). The markers were used to determine the basis position and then correct the data of sample by the migration time of standard sample, and make the migration time of samples consistent with the standard sample by the criterion of the marker. The problem of time transition was corrected in this way. Then according to the peak height or peak area of the marker in the sample (peak height was used here) compared with the standard sample, the sample data was zoomed appropriately. The absorbance error was made to be correct. The wavelet de-noise method was also used to make the data smooth and get a good baseline. 相似文献
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Chui Lin RONG Xin Cheng LIAO Jian Chen ZHANG Shu Xia CAO Lun LIU Yu Fen ZHAO 《中国化学快报》2005,16(9):1140-1142
Different hydroxy substituted coumarins were successfully phosphorylated with diisopropylphophite (DIPPH) by the Atherton-Todd reaction in 76-89% yields. Moreover, the reaction activities of different hydroxys of the coumarins in the Atherton-Todd reaction were studied. 相似文献
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The influence of an anionic polysaccharide, κ-carrageenan, on the rheological properties of low-concentration (1.0 wt %) gelatin gels has been studied in a wide range of low polysaccharide concentrations (1 × 10?3–5 × 10?1 wt %) at a temperature of 14.0°C and pH values slightly higher than the isoelectric point of gelatin. The parameters characterizing the rheological properties of the gels are governed by the mass ratio between the polysaccharide and gelatin, which are able to form (bio)polyelectrolyte complexes in aqueous systems. There is a critical κ-carrageenan-to-gelatin mass ratio Z ? 0.1, above which the yield stress of the gels and their effective viscosit at stresses exceeding the yield point drastically rise. The increase in these rheological parameters correlates with a growth in the particle size of κ-carrageenan-gelatin polyelectrolyte complexes, which are formed in the aqueous bulk phase at an elevated temperature and precede gelation. 相似文献
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The Synthesis of Cyclic Amino Acids 总被引:4,自引:0,他引:4
ShrongShiLIN JingYuanLIU JianMeiWANG 《中国化学快报》2003,14(9):883-884
Several cyclic amino acids (1-4) were synthesized from glycine. Isocyanate ester was prepared as the key intermediate and reacted with dibromoalkanes to afford the target compounds. 相似文献